java.lang.NoClassDefFoundError: Could not initialize class org.apache.commons.logging.LogFactory

Question

I am new to Google App Engine. I am getting this error :

java.lang.NoClassDefFoundError: Could not initialize class 
                  org.apache.commons.logging.LogFactory at
org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:282) at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:106) at 
org.mortbay.jetty.handler.ContextHandler.startContext(ContextHandler.java:548) at 
org.mortbay.jetty.servlet.Context.startContext(Context.java:136) at ...

I have added slf4j dependencies and excluded commons-logging in spring-context dependency but still getting this error. The app works perfectly fine on my local machine but gives me this error when deployed to the App Engine.

Answer 1

Thanks to this blog , I was able to resolve this issue :

Commons-logging is a dependency of many frameworks, Spring included. On the local server, everything runs fine. In effect, that means you get funny NoClassDefFoundError on org.apache.commons.logging.LogFactory even though you included the JAR as a dependency. The solution is to still include the classes, but to give the JAR another name.

Since I use Maven, I removed the commons-logging dependency from the WAR with the exclusion tag for Spring and MyFaces artifact. Then, I added a dependency on commons-logging:commons-logging-api:1.1:jar with the runtime scope. This jar won't be replaced.

So you should exclude commons-logging from Spring :

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-webmvc</artifactId>
    <version>${org.springframework.version}</version>
    <exclusions>
        <exclusion>
            <groupId>commons-logging</groupId>
            <artifactId>commons-logging</artifactId>
        </exclusion>
    </exclusions>
</dependency>

Then add a dependency on commons-logging-1.1 with runtime scope:

<dependency>
        <groupId>commons-logging</groupId>
        <artifactId>commons-logging-api</artifactId>
        <version>1.1</version>
        <scope>runtime</scope>
</dependency>

Answer 2

You are missing a required jar in your /war/WEB-INF/lib/ folder. It's not enough to have it in your classpath.

If you use Eclipse, you should see a warning in the Problems tab. Right click on it, Quick Fix, select " Copy ...". Or add this jar to the /lib folder manually.